The present invention relates to an acceleration sensor, and more particularly, relates to an acceleration sensor attached to an inclining member such as a seatback or the like of a vehicle, which sensor is not affected by inclination of this inclining member in detecting acceleration of the vehicle.
In some acceleration sensors for detecting acceleration of a vehicle or the like, a sensor ball (moving body) of a fixed mass is mounted on a supporting surface of a supporting body of a bracket or the like. The sensor ball, when receiving an acceleration larger than or equal to a predetermined value, drives an output member by being inertially moved by the acceleration.
For cases where this type of acceleration sensor is attached to a member that inclines such as a seatback of a vehicle or the like, there is a type of acceleration sensor (what is known as an interlock follow-up system), in which a portion of a seat of a vehicle and a bracket are connected by a connecting member such as a wire, and when the seatback inclines, this bracket is forcibly rotated by the connecting member so as to maintain a supporting surface of the bracket at a predetermined angle. This interlock follow-up system acceleration sensor can detect a predetermined acceleration even when a seatback is in a reclining posture.
However, when the angle of inclination of the inclining member exceeds a certain range, there are cases in which it is no longer necessary to detect the acceleration with the acceleration sensor (for example, a state in which a seatback is collapsed forward, in a case of an acceleration sensor attached to a seatback of a vehicle, or the like). However, if the supporting body is made to interlock with the inclining member in a simple manner, even when the angle of inclination of the inclining member exceeds this certain range, the supporting body rotates with respect to the inclining member at the same angle as the angle of inclination of the inclining member. As a result, a predetermined space must be provided at the inclining member in consideration of this rotational path, which lowers space efficiency.
In consideration of the aforementioned circumstances, the present invention has as an object obtaining an acceleration sensor that can detect reliably acceleration when inclination of an inclining member is in a fixed range, and whose space usage efficiency within a device is high.
In order to achieve the above-described object, in a first aspect of the present invention, an acceleration sensor comprises: a supporting body attached to an inclinable inclining member so as to be rotatable at least about an axis parallel with an inclination center of the inclining member; a moving body supported at the supporting body, for driving an output member by being inertially moved by an acceleration of a predetermined value or more; angle maintaining means for interlocking with inclination of the inclining member to maintain the supporting body at a fixed angle with respect to the horizontal plane; and interlock prevention means for, when the inclining member inclines exceeding a predetermined angle of inclination, preventing interlock of the angle maintaining means with respect to the inclining member and fixedly maintaining a relative position of the angle maintaining means with respect to the inclining member.
According to this first aspect, when the inclining member inclines exceeding a predetermined angle of inclination, interlock of the angle maintaining means with respect to the inclining member is prevented by the interlock prevention means, and the relative position of the angle maintaining means with respect to the inclining member is fixedly maintained. As a result, the angle of the supporting body with respect to the inclining member is fixedly maintained.
Namely, in a state in which the angle of inclination of the inclining member exceeds a predetermined angle of inclination, the supporting body does not rotate with respect to the inclining member, and therefore a space does not need to be provided in light of this rotation, and space efficiency inside the device becomes high. Further, since a phase difference (a difference in relative positions) is not generated between the angle maintaining means and the inclining member, deviation is not generated in the angle of the supporting body with respect to the inclining member either, and the supporting body is maintained at a fixed angle with respect to the horizontal plane by the angle maintaining means.
Thereafter, when the inclining member is moved in the direction of returning to the original state, the interlock prevention means cancels interlock prevention of the angle maintaining means with respect to the inclining member. As a result, within a range of a predetermined angle of inclination, the supporting body can be maintained at the predetermined angle with respect to the horizontal plane by the angle maintaining means.
In particular, in a state in which the inclining member inclines exceeding the predetermined angle, the interlock prevention means fixedly maintains the relative position of the angle maintaining means with respect to the inclining member. Therefore, when the interlock prevention is canceled by the angle maintaining means, a phase difference is not generated between the angle maintaining means and the inclining member. As a result, deviation does not occur in the angle of the supporting body with respect to the inclining member either, and the supporting body is maintained at a fixed angle with respect to the horizontal plane by the angle maintaining means.
In a second aspect of the present invention, the angle maintaining means comprises: a fixed gear body fixed coaxially with the inclination center of the inclining member; and a revolving gear body attached to the inclining member so as to be able to revolve with respect to the fixed gear body to thereby mesh with the fixed gear body, and the interlock prevention means comprises: a releasing portion for releasing meshing of the fixed gear body and the revolving gear body when the inclining member inclines exceeding a predetermined angle of inclination; and a fixing portion for, when the meshing of the fixed gear body and the revolving gear body is released, fixing the revolving gear body such that relative rotation thereof with respect to the inclining member is impossible.
According to this second aspect, since the releasing portion releases meshing of the fixed gear body and the revolving gear body when the inclining member inclines exceeding the predetermined angle of inclination, rotation (interlock with respect to the inclining member) of the revolving gear body is prevented. Further, in a state in which this meshing is released, the fixing portion fixes the revolving gear body such that the revolving gear body is unable to undergo relative rotation with respect to the inclining member.
As a result, the revolving gear body is maintained at a fixed position relative to the inclining member, and the supporting body is also maintained at a fixed position with respect to the inclining member. When the revolving gear body is returned to a position of meshing with the fixed gear body, a phase difference is not generated between the revolving gear body and the fixed gear body. Deviation does not occur in the angle of the supporting body with respect to the inclining member either, and the supporting body is maintained at the fixed angle with respect to the horizontal plane.
In a third aspect of the present invention, with the invention according to claim 3, in the invention according to claim 1, the angle maintaining means comprises: a rotating body fixed at the supporting body so as to be rotatable about the rotational axis of the supporting body; and rotating means for interlocking with inclination of the inclining member so as to be able to rotate the rotating body in the opposite direction to the inclination direction of the inclining member and at the same angle as the inclination of the inclining member, and the interlock prevention means comprises: an abutting portion for preventing relative rotation of the supporting body with respect to the inclining member by abutting the supporting body when the inclining member exceeds a predetermined angle; and allowing means for, in a state in which the abutting portion has abutted the supporting body, allowing the rotating means to rotate relatively to the rotating body.
Namely, when the inclining member is inclined, the rotating means interlocks with this inclination and rotates the rotating body in the opposite direction to the inclination direction of the inclining member and at the same angle as the inclination of the inclining member. As a result, the supporting body also rotates, and the supporting body is maintained at the predetermined angle with respect to the horizontal plane.
According to this third aspect, since the abutting portion abuts the supporting body and thus prevents relative rotation of the supporting body with respect to the inclining member when the inclining member inclines exceeding the predetermined angle of rotation, interlocking of the supporting body with respect to the inclining member is prevented. Further, in a state in which the abutting portion abuts the supporting body, the allowing means allows the rotating means to rotate relatively with respect to the rotating body. As a result, the rotating means becomes independent from the rotating body in correspondence with the angle of inclination of the inclining member, to interlock with the inclining member and rotate. Accordingly, when the supporting body separates from the abutting portion and becomes able to undergo relative rotation with respect to the inclining member, a phase difference is not generated between the rotation means and the rotating body. Deviation in the angle of the supporting body with respect to the inclining member is not generated either, and the supporting body is maintained at a fixed angle with respect to the horizontal surface.